1. Field of the Invention
The present invention relates to a method for verifying data matrix print quality. More particularly, the present invention relates to a method of verifying the quality of two dimensional part marks on all types of direct part marking applications and label marking applications. The overall symbol grade, symbol contrast, print growth, axial non-uniformity, unused error correction, and other parameters relating to direct part marking are identified.
2. Description of the Prior Art
One and two dimensional part marks have achieved wide spread acceptance throughout a wide variety of industries. At most, systems and devices for reading such one and two dimensional symbols begin by determining the orientation of the markings before trying to read the symbol. Usually this is done by locating an outer reference bar(s) or a central symbol. Once the orientation of the marking is determined, the marking is read.
The term data matrix has been certified by AIM-USA and AIM-International as a fully public-domain symbology. AIM stands for Automatic Identification Manufacturers International, Inc. The data matrix is a unique machine readable symbol capable of storing a large amount of information within a small physical size. The data matrix symbol allows for two-dimensional encoding and decoding. Users are not constrained by the limitations of a printed symbol. Data matrix symbols are capable of carrying 25 to 100 times more information than the typical barcode. This range is directly related to the image quality the printer is capable of producing.
Data matrix codes have the following characteristics: both height and width are used to encode data, works with contrast as low as 20%, readable through 360.degree. of rotation, designed to survive harsh industrial environments, codes can be marked on the surface of a part, without using a paper label, and several error correction schemes are available to ensure damage recovery.
No method or system has been developed for determining the quality of the part markings.